Tens of thousands of demonstrators marched through the streets of Brazil’s biggest cities on Monday in a growing protest that is tapping into widespread anger at poor public services, police violence and government corruption.

The marches, organized mostly through snowballing social media campaigns, blocked streets and halted traffic in more than a half-dozen cities, including Sao Paulo, Rio de Janeiro, Belo Horizonte and Brasilia, where demonstrators swarmed past the Congress and Presidential Palace.

While peaceful, and unfolding mostly as a festive display of dissent, Monday’s demonstrations were the latest in a flurry of protests over the past two weeks that have added to unease over Brazil’s sluggish economy, high inflation and a spurt in violent crime.

The marches began this month with a small protest in Sao Paulo against a small increase in bus and subway fares. The demonstrations initially drew the scorn of many middle-class Brazilians after protesters vandalized storefronts, subway stations and buses on one of the city’s main avenues.

But the movement quickly gained support and spread to other cities as police used heavy-handed tactics to try to quell the demonstrations. The biggest crackdown happened on Thursday in Sao Paulo when police fired rubber bullets and tear gas in clashes that injured more than 100 people, including 15 journalists, some of whom said they were deliberately targeted.

The protests have gathered pace as Brazil is hosting the soccer Confederation’s Cup, a dry run for next year’s World Cup. The government hopes these events, along with the 2016 Summer Olympics, will showcase the country as an emerging power on the global stage.

Brazil is also gearing up to welcome more than 2 million visitors in July as Pope Francis makes his first foreign trip for a gathering of Catholic youth in Rio.

Contrasting the billions in public money spent on new stadiums with the shoddy state of Brazil’s public services, protesters are using the Confederation’s Cup as a counterpoint to amplify their concerns. The tournament got off to shaky start this weekend when police clashed with demonstrators outside stadiums at the opening matches in Brasilia and Rio.

“We shouldn’t be spending public money on stadiums,” said one protester in Sao Paulo who identified herself as Camila, a 32-year-old travel agent. “We don’t want the Cup. We want education, hospitals, a better life for our children.”

Other common grievances at Monday’s marches included political corruption and the inadequate and overcrowded public transportation networks that Brazilians cope with daily.

POLICE ORDERED TO USE RESTRAINT

The harsh police reaction to last week’s protests touched a nerve in Brazil, which endured two decades of political repression under a military dictatorship that ended in 1985. It has also added to doubts about whether Brazil’s police forces would be ready for next year’s World Cup.

Jose Vicente da Silva, a security consultant and retired police colonel, said training for the big events has focused too much on elite forces instead of the rank-and-file officers who must face the public.

The clashes, he said, “suggest that the everyday policeman in Sao Paulo has barely trained at all” in how to handle a demonstration.

The uproar following last week’s crackdown prompted Sao Paulo state Governor Geraldo Alckmin, who initially described the protesters as “troublemakers” and “vandals,” to order police to allow Monday’s march to proceed and not to use rubber bullets.

The protests are shaping up as a major political challenge for Alckmin, a former presidential candidate, and Sao Paulo’s new mayor, Fernando Haddad, a rising star in the left-leaning Workers’ Party that has governed Brazil for the past decade. Both have so far insisted that the bus fare hike that sparked the protests is non-negotiable.

Brazilian President Dilma Rousseff, who has enjoyed high approval ratings since taking office in 2011, only recently began to slip in opinion polls. Although the protests have gained traction, they do not appear to reflect any broad-based collapse in her support, but Rousseff was booed at Saturday’s Confederations Cup opener.

Still, the resonance of the demonstrations underscores what economists say will be a challenge for Rousseff and other Brazilian leaders in the years ahead: providing public services to meet the demands of the growing middle class.

“Voters are likely to be increasingly disgruntled on a range of public services in a lower growth environment,” Christopher Garman, a political analyst at the Eurasia Group, wrote in a report.